Various wireless cellular telecommunication systems are known from the prior art, some of which have been standardized. A common feature of such wireless cellular telecommunication systems is that the network has a number of access points for coupling of mobile nodes to the wired backbone of the system. Each of the access points defines a cell having an assigned frequency in accordance with a certain frequency reuse pattern. In the case of GSM the access points are commonly referred to as “base transceiver stations” and in the case of UMTS the access points are commonly referred to as “node-Bs”.
In addition, so called ad hoc networks have been investigated (cf. “performance evaluation of modified IEEE 802.11 MAC for multi-channel, multi-hop ad hoc network”, Li et al, http://wnl.ece.cornell.edu/Publications/aina03.pdf, A highly reliable broadcast scheme for IEEE 802.11 multi-hop ad hoc networks, Shiann-Tsong Sheu, Yihjia Tsai, Jenhui Chen; Communications, 2002. ICC 2002. IEEE International Conference on Pages:610-615; 2002). It is to be noted that ad hoc networking is possible with the standard IEEE 802.11 only on a single frequency channel.
Ad hoc wireless networks are constructed by several mobile handsets or laptops and characterized by multi-hop wireless connectivity, constantly changing network topology and the need for efficient dynamic routing protocols. There is no stationary infrastructure or base station to coordinate packets transmissions and distribute the information of network topology. According to these characteristics, each mobile node in the multi-hop ad hoc networks must act as routers, relaying data packets to their neighboring mobile nodes. Since network resource is limited, any transmission will interfere the neighbors, which also have packets to transmit in the same radio channel.
For multi-channel, multi-hop, IEEE 802.11 ad hoc networks two basic methods are known: the Measurement-Based Method and the Status-Based Method. In the Measured-Based Method, a node is equipped with the capability to measure either the signal strength, the signal to noise ratio, or the signal to interference ratio. A node periodically scans each channel to find the channels with acceptable interference conditions. In the Status-Based Method, each node acquires the channels' Busy/idle status through listening to the MAC-layer control packets. Based on the channel status, an available channel is selected for use.
The present invention aims to provide an improved wireless cellular telecommunication system and an improved method and computer program for operating of such a telecommunication system.